Platen press with simultaneous-closure means



Nov. 12, 1968 E. SIEMPELKAMP 3,409,942

PLATEN PRESS WITH SIMULTANEOUS-CLOSURE MEANS Filed Oct. 4. 1966 3 Sheets-Sheet 1 Pressure -Thresholcl 4b \mv'llllmil Eugen S/empelkamp 1.\'\ 'E.\'T()R.

Nov. 12, 1968 E. SIEMPELKAMP 3,409,942

PLATE-N PRESS WITH SIMULTANEOUS-CLOSURE MEANS 3 Sheets-Sheet 2 Filed Oct. 4, 1966 Nov. 12, 1968 SIEMPELKAMP 3,409,942

PLATEN PRESS WITH SIMULTANEOUS-CLOSURE MEANS Filed Oct. 4. 1966 3 Sheets-Sheet :5

Eugen Siempelkamp INVENTOR.

93" Wk Attorney Un t St t s P te My present invention relates to a multiplaten press plate and bed plate of the press can be displaced relatively toward one another with a stack of platens therebetween, the simultaneous-closure device elevating the platens to close the gaps therebetween concurrently with movement of the bed plate or head plate thereof.

In my US. Patent No. 3,050,777 of Aug. 28, T1962, and the commonly assigned Patent No. 3,209,405 of Kurt Lowenfeld, there are described simultaneous-closure devices for the platens of a multiplaten press which reduce the gaps between the platens in step with the elevation of the bed plate so that the latter and the lower platens need not carry the load of successive platens as is common in multiplaten presses which do not have simultaneous-closure devices. In the simultaneous-closure devices of these patents, cables extend to the individual platens from Windlass systems of different diameters (corresponding to the position of the platens in the'stack), the windlasses being, in turn, rotated by the movable press member (i.e., the head plate or bed plate). It has also been proposed, however, to provide simultaneous-closure devices for platen-type presses in which the displacement of the platens at rates corresponding to the rate of the advance of the movable press member (i.e., the head plate, bed plate or both) avoid the use of a Windlass and substitute therefor a control lever. Platen presses of this general type are characterized by differentially movable bed plates and head plates guided in common support means and mutually displaceable toward andaway'from a horizontal median plane between thesemovable press members. The press members are coupled together by swingable control levers which are articulated to the press and head plates for mirror-symmetrical movement about parallel axes in a common vertical median plane of the press. The head plate of such a press is then connected via suspension rods of adjustable length tothe individual press platens which were resiliently supported by these rods. The rods were, moreover, joined to control levers lying in a vertical median plane of the press at distances from the fulcrum corresponding to the distance through which the individual platen was required to move, means being provided for swinging these latter levers about their respective fulcra in step with press closure.

All of these conventional simultaneous-closure devices for platen presses were characterized by significant disadvantages in a geometrical and kinematic sense. Inasmuch as force transfer from the platens to the closure device applied considerable strain upon the control levers, it was necessary to dimension them with sufiicient size to withstand the strain. Moreover, since the effective displacement of the platens is a function of the thickness of the mat of fibers or chips to be compressed, some platens encounter resistance whileothers remain relatively freely displaceable. Consequently, the strainsapplied to the control levers are nonuniform and, asa practical matwith a simultaneous closure' means 'whereby' the head ice ; Thus it ha s been determined that conventional suspension spring methods of supporting the platens from the control lever of the simultaneous-closure device are inadequate in taking up inequalities in the thickness of the m'aterialto becompressed and in eliminatingnonuniform stresses "applied to these control levers. Moreover, when distortion and damage to the deviceis almost a certainty fand it is almost equally certain that some of the plates will be compressed to a greater extent than others. In fact, a buckling of the control levers is not uncommon.

It is, therefore, the principal object of the present invention to provide an improved multiplaten press having simultaneous-platen closure means, of relatively low capital cost, which eliminates the danger of buckling or overstressing, can be dimensioned to be much smaller than prior simultaneous-closure systems, and ensures a uniform compression of the mats carried by the platens in spite of possible absence of one or more such mats or the presence of a double thickness thereof between two of the platens.

Another object of this invention is to provide an improved simultaneous-closure device for the platens of a multiplaten press which is capable of transmitting uniform press-closing force to all of the layers between the platens, the bed plate and the head plate. Still another object of my invention is to provide a multiplaten press having a greatly simplified simultaneous-closure device free from the disadvantages of prior closure devices of the type discussed above.

These objects and others which will become apparent hereinafter are attainable, in accordance with the present invention, with a simultaneous-closure device comprising a control lever hingedly connected with one of the press members (e.g., the head member or the bed member), and preferably the stationary head plate, from which individual connecting members or elements extend to the individual press platens, these members being tied to the control lever at locations spaced from the fulcrum thereof at distances corresponding to the distance of the respective platen from the fulcrum plate. In accordance with an important feature of this invention, each of these necting elements and the control lever; the control lever is, in turn, provided with means connecting it with the movable press member (e.g., the bed plate) for swinging the control lever about its fulcrum during closure of the press.

Thus, in accordance with the present invention, a forceequalizing system is provided between the connecting elements and the control lever to ensure that each of the platens will be held against the adjacent platens and will compress any layer disposed thereon with the same pressure as applied by the other platens to their respective layers. The connecting elements can, according to this invention, be constituted as rods of adjustable length with or without resilient means for elastically transmitting forces through these rods. Alternatively, the connecting elements can be tensionable members, such as flexible cable, chain or the like.

The force-transmitting devices of the equalizing means can include hydraulic, pneumatic, hydraulic/pneumatic or mechanical elements as will become apparent hereinafter. When a fluid-responsive force-transmitting means is employed, itcan be constituted as a piston-and-cylinder arrangement interposed between an end of the respective connecting element and the control lever, the fluid chambers of all of the piston-and-cylinder arrangements being connected via suitable conduit means in parallel. If the fluid-responsive means isoperated with a pneumatic medium, no pressure accumulator is required in view of the compressibility of the medium, whereas use: of a hydraulic medium will'necessitate a pressure accumulator of any conventional type. It has been found to be highly advantageou's, however, to operate with a practically incompressiblefiuid connected in a hydraulic circuit with highpressure threshold pressure-relief valves operating in both directions and establishing the sensitivity of the equalization system. The return of the pistons of the piston-andcylinder arrangements into their original positions upon opening of the press can be effected by means of the weight of the platens themselves, some auxiliary means such as the camming devices disclosed in US. Patent No. 2,792,777, or means acting upon the force-transmitting arrangements as set forth below.

According to another feature of the present invention, the force-equalizing means is purely mechanical inasmuch as the mechanical system is suitable for use with presses having large numbers of platens and in situations where fluid leakage or the like warrants avoidance of fluid-responsive systems. The mechanical force-equalizing system advantageously comprises a multiplicity of pulleys mounted upon the respective connecting elements at their ends adjoining the control lever and serving as the force- .transmitting means. These pulleys, which are joined together in parallel and to the control lever by a tensionable flexible member (e.g. a cable or chain) are thus effectively connected in parallel so that the forces applied to all of the connecting elements are equal. In addition to this tensioning cable and roller arrangement, the ends of the connecting elements can be spring-loaded or provided with fluid-responsive means of the type set forth above.

-The principal advantage of the system described above is that the forces applied by the several connecting elements to the respective platens is identical for all platens regardless of variations in the thickness of the mat carried thereby and the degree of platen displacement during .press closure.

The principal advantage of the system described above is that the forces applied by the several connecting elements to the respective platens is identical for all platens regardless of variations in the thickness of the mat carried thereby and the degree of platen displacement during press closure. Moreover, unequal forces are not applied to the simultaneous-closure device so that the control lever can be made of relatively less massive construction than has characterized earlier press-closure systems. The

pressureor force-equalizing means permits mutual movement of the platens through different distances without corresponding variation in the pressures applied thereby to the respective mass and without involving the danger that the full press forces will be applied to the connecting not permit nonuniform movement of the platens but the presence of a double thickness of a compressible mat or the absence of a mat will bring the pressure or forceequalizing means into play.

The above and other objects, features and advantages of the present invention will become more readily appar- 4 ent from the following description, reference. being made to the accompanying drawings in which:

FIG. 1 is a diagrammatic vertical cross-sectional view through one side of a multipla ten press embodying the present invention; I

FIG. 2 is an elevational'view of apress 'having'a' modified press-closure device according, to the invention; and

FIG. 3 'isfa view similar'to FIG. l illust rating-. the closure device of the press of FIG. 2 ina ,closed state, the platens being provided with compressible layers.

In FIG. 1 of the drawings-,1 show .the left side of a multiplaten press which can have the general construction illustrated in any of the'aforementioned patents and is provided with hydraulic means for displacing the bed plate or lower press member 1 in the direction of the head plate or upper press member 2. The latter is fixed in a frame of the typddescribed in US. Patent 'No. 3,209,405 or No. 3,050,777. Between the 'fixed'head 2 and the movable bed 1, which can be provided'with heated plates 3 as described in'iny Patent No. 3,241,189 issued Mar. 22, 1966;f'or heating the loosely coherent fiber, laminate stack of wood, veneers, layers of wood chips with or without added hinder, or the like to apply heat and pressure capable of transforming the layers into coherent board or plates, I" dispose a muitiplicity of heated platens 4. The resulting product, which ca'ri'be a wood laminate such as plywood or veneer, 'a fiberboard of the porous or cellular type, or a highly compressed 'impermeable composite board, is removed from the press and subjected to tempering, kiln drying or the like. Suitable means for charging and discharging the press are illustrated and described in my Patents No. 3,050,200 of Aug. 21, 1962, and No. 3,077,271 of Feb. 12, 1963'. The heated platens 4 are disposed in stacked relationship between the stationary head plate2 and the vertically displaceable bed plate 1', the platens for each being designed to receive a respective layer to be compressed in the usual manner.

According to an important feature of the present invention, the press of FIG. 1 is provided symmetrically on opposite sides thereof with a simultaneous platenclosure mechanism A (only the left-hand closure device being illustrated in FIG. 1). The platen-closure device A at each side of the press comprises a control lever 5 whose fulcrum 5a is fixed with respect to the stationary press member 2 and is here defined by a journal box 51) affixed to the head plate 2 via bolts 50. The journal box 512 is mounted upon the head plate 2 along its flank. The lever 5 carries a plurality of hydraulic piston-andcylinder arrangements 7 corresponding in number to the vertically movable platens 4, pivoted in the lever 5 upon pins 7a and having pistons 7b (shown intheir normal positions) respectively connected to the suspension elements 6 at corresponding extremities thereof. Each of the connecting elements 6 has an eye 6a through which the pin 6b of the respective platen passes so that the connecting element 6 can be considered swingably connected to the respective platens at the lugs 6c thereof. To swing the lever 5, I provide a rod'Sd which is journaled at its lower end Se in a journal block 5) fastened to the flank of the bed plate 1. At its opposite end 5g the bar So! is articulated to the arm 5. Thus elevation of the bed plate 1 relative to the head plate' 2 eflects-a swinging movement of the control lever 5 about its pivot or fulcrum 5a in the clockwise sense. Conversely, a downward movement of the bed plate 3 will result in a counterclockwise movement of the lever 5. A similar bar 5d is provided on the opposite side of the press so that the arms 5 of the simultaneous-closure device 5a are displaced symmetrically. 1

The pressurizable chambers 70 of the piston-and-cylinder arrangements 7 are connected together in parallel by the conduits 7d (dot-dash lines in FIG. 1) and with ,a fluid reservoir -8. When the fluid is an incompressible hydraulic liquid, the reservoir 8 can constitute a forcestoring accumulator in which the. hydraulic fluid acts against a resiliently compressible gas, a force-restoring spring or the like. Similar accumulators may include weights, membranes etc. against which thehydraulic fluid may act. It will be understood that the chambers 70 of-the force-transfer devices can be connected in tandem via lengths of tubing extending from one frcetransfer arrangement to another with the same effect. The upper end 7e of the cylinders 7g of each force-transfer device can be open tothe atmosphere via a venting valve permitting both intake and expulsion of air from the chambers above the respective piston 7b or may be connected to an oil-leakage line designed to gather. any hydraulic fluid which may pass the respective piston. The chamber 7c, the duct 7d and the hydraulic-pressure accumulator 8 form a closed system into which eachof the chambers -7c opens so that the identical forceis applied to each of the connecting cables or rods 6 andthe respective platen 4. Turnbuckles 13 permit initial adjustment of the heights of-the individual platens 4.

As the bed platel rises'upon actuation of the usual hydraulic cylinders of the press, the bar d swings the lever 5 about the fulcrum 5a in the clockwise sense. For each increment of upward movement of the bed plate 1, therefore, the lever 5 is incrementally swung about its fulcrum and each of the platens 4 lifted via the respective connecting rods 6 by a corresponding increment and at a rate in proportion to the distance of the platen from the head plate 2 or the distance from the fulcrum 5a at which the respective cylinder arrangement 7 is pivotally anchored to the lever 5. Under normal conditions, when no compressible layers are present the bed plate 1 will engage the platen '4 thereabove in the closed condition of the press simultaneously with contact between each platen and the platen thereabove. Similarly, when all of the platens 4 carry compressible layers of identical thickness and compressibility, a uniform compression of all layers will take place. When one of the platens 4 carries a double-thickness layer and/ or another platen fails to be provided with a layer, upward press-closing movement of the platens 4 and the bed plate continues until further movement of one of the platens is restricted by engagement of its layers with the platen thereabove. Continued counterclockwise movement of the lever 5 will thereupon take place to compress the chamber 70 of that platen and thereby force hydraulic fluid under the same pressure into each of the other chambers 70, thereby expanding them if the respective platens are free to move upwardly. Consequently, press-closing action continues with the same force applied to the platens during press closure regardless of whether the particular platen is immobilized or may move freely. During press-opening operation, the counterclockwise rotation of the lever 5 lowers the platen 4 at a rate proportional to the distance of the platen from the head plate 2. Instead of an accumulator or in addition thereto, pressure-threshold valves 8a may be pro vided between the reservoir 8 and the line to establish the hydraulic loading of the system.

In FIG. 2, I show one of a symmetrical pair of simultaneous-closure arrangements B of a multiplaten press in accordance with another aspect of this invention. In this system, the bed plate 101 is provided with a heated platen surface 103 and is movable upwardly to compress a layer of loosely coherent material against the platens 104 thereabove. The head plate 102 is also provided with a heated platen 103'. A swingable control lever 105 is pivotally mounted at 105a on a journal block 1051; to the head plate 102. This lever is, moreover, articulated at 105g to the rod 105d which, in turn is hinged at 105a to the journal block 105 along a flank of the bed plate 101. In this embodiment, however, a flexible tension cable 107d serves as the force-equalizing means in place of the hydraulic network 7d of FIG. 1. The cable 107d passes over a multiplicity of idler pulleys 109, each mounted upon arespective-pedestal 109a between a pair of force-transfer elements here represented as pulleys 111. The pulleys 111 engage the bridging member or tension cable 107d between the idler rollers 109 and are rotatable at the extremities of the respective suspension elements 106. The latter may be formed as cables or rods and again are provided with turnbuckles or tensioning devices 113 to set the original height of each platen 104. Each of the pulleys 111 is, moreover, aligned with a respective brake shoe 114b which is held thereagainst by a compression spring or pneumatic spring formed in a respective housing 114a or, when the housing 114a is rigid with the respective brake shoe 1141), via a beam 114 carrying the brake shoes and held against the rollers via springs 115. The springs can be stressed by double-acting hydraulic cylinders 115a at each end of the lever 105. The cable 107d is pretensioned against the-rollers 111 via coil springs 112 seated against caps 112a fixed to the respective extremities of the cable. The spring means 112 is representative of any stressing device and can :be constituted by a hydraulic or pneumatic cylinder, a crank .or Windlass or the like. The tensioning cable 107d can be representative of an array of parallel wires each of which passes over a respective pulley, the pulleys being ganged in axial direction and being connected via a corresponding number of wires to the respective platen in the manner illustrated with connecting element 106. Under these circumstances, the rollers 109 and 111 can have relatively small diameters, leading to a compact construction of the simultaneous-closure device.

The operation of the system of FIG. 2 is generally similar to that described in connection with FIG. 1 except that rotation of a roller 111 is only permitted when the upward movement of the respective platen 104 is re sisted by a force of a predetermined magnitude corresponding to that necessary to overcome the braking force of the pulley 111. When such a force is attained, the pulley 111 of the immobilized platen 104 will lengthen the corresponding loop of the tension member (i.e. cable) 107d and increase the force applied thereto. This force will tend to raise the other roller 111 and maintain the equalized force throughout simultaneous closure of the press. When the brake shoes 11412 are springloaded as illustrated in FIG. 2, or double-acting cylinders 115a are actuatable to bring the brake shoes into play, the brake shoes act as repositioning means for displacing the pulleys 111 into their original or normal positions.

From FIG. 3, the mechanism whereby identical pressures are applied to the platens in spite of the presence of a. double thickness of compressible material or the absence of a compressible layer will become apparent. In the closed condition of the press, the platens 104a, 104b, 104e, 104d and 104e carry the usual single-thickness layer of a compressible mat for the production of a fiberboard. Platen 104 however, has not received a layer and bears directly against the platen 104d whereas the platen 104g carries a double thickness of the fiberboard mass. As the movable bed plate 101 rises under the action of the hydraulic cylinders 120, therefore, the gaps between the platens close at a rate corresponding to press closure so that, under normal circumstances, all of the platens will compress their layers against the next-higher platen at the final point of press closure. Because of the presence of a double thickness of mat upon the platen 104g, this platen encounters resistance even before the remaining mats contact the next higher platens. The resistance, when sufi'icient to overcome the braking force of the respective friction brake 114b tensions the cable 107d so that the identical force is applied to the remaining platens. Nonloaded platens 104] thus can rise more readily so that, in the end positions of the platens, they are pressed together with identical forces and any irregularity of the space between them is fully compensated.

The invention described and illustrated is believed to admit of many modifications within the ability of persons skilled in the art, all such modifications being considered within the spirit and scope of the appended claims. I claim: I 1. In combination with a multiplaten press having a head plate and a bed plate, means for relatively displacing said plates toward and away from one another, and a multiplicity of vertically stacked platens disposed between said plates for simultaneous compaction of individual layers of compressible material positionable between said platens: at least two simultaneous-closure devices connected with said platens for displacing same synchronously with the relative movement of said plates, said devices each comprising a lever fulcrumed to one of said plates f01'.sWinging movement about a generally horizontal axis;

means operatively connecting said lever with the other of said plates for swinging displacement of said lever about its fulcrum synchronously with the relative movement of said stationary plates; connecting means individual to said platens and coupled with said lever at spaced locations; and

force-equalizing means including respective forcetransmitting means interposed between said lever and each of said connecting elements for transferring forces from said lever to said connecting elements, and bridging means connecting said force-transmitting means to equalize the stresses applied by said lever to all of said connecting elements at least at end positions of the platens corresponding to press closure.

2. The combination defined in claim 1 wherein said head plate is relatively stationary and said bed plate is shiftable vertically toward and away from said head plate, the levers of said simultaneous-closure devices each being fulcrumed to said head plate, said means operatively connecting said levers with said other of said plates including respective rods articulated to each of said levers and hinged to said bed plate, said connecting elements forming suspension means supporting said platens from said levers.

3. The combination defined in claim 1 wherein said force-transmitting means includes a pulley affixed to each of said connecting elements, said lever being provided with an array of rollers disposed between said pulleys, said bridging means including an elongated tension member passing around said rollers and said pulleys for distributing the stresses applied by said lever equally among said connecting elements.

4. The combination defined in claim 3, further comprising means for yieldably pretensioning said member.

' '5. The combination defined in claim 3, further comprising means for individually adjusting the length of said connecting elements. Q

6. The combination defined in claim 3, further comprising brake means respectively co-oper-ating with said pulleys for restricting movement thereof under the action of said member until the press-closure resistance applied to a respective platen exceeds a predetermined level.

7. The combination defined in claim 3, further comprising means for resetting said pulleys to respective normal positionsupon movement of said pulleys out of said normal positions during press closure. I 1

8. The combination defined in claim 1 wherein said force-transmitting means includes a respective fluid-responsive arrangement interposed between said lever and each of said connecting elements, said arrangements having corresponding fluid chambers of variable volume, said bridging means including duct means interconnecting said chambers.

9. The combination defined in claim 8, further com.- prising yieldable means connected with said bridging means for applying an elevated pressure to the fluid in said compartments.

10. The combination defined in claim 9, further comprising means for individually adjusting the lengths of said connecting elements. 1

References Cited UNITED STATES PATENTS 3,050,777 8/1962 Siempelkamp 18-16 3,209,405 10/ 1965 Loewenfeld 18-16 3,286,304 11/1966 Falkinger et al. 1817 3,361,056 1/1968 Carlsson et al. 18l7 3,368,242 2/1968 Loewenfeld et a1 1817 I. HOWARD FLINT, 1a., Primary Examiner. 

1. IN COMBINATION WITH A MULTIPLATEN PRESS HAVING A HEAD PLATE AND A BED PLATE, MEANS FOR RELATIVELY DISPLACING SAID PLATES TOWARD AND AWAY FROM ONE ANOTHER, AND A MULTIPLICITY OF VERTICALLY STACKED PLATENS DISPOSED BETWEEN SAID PLATES FOR SIMULTANEOUS COMPACTION OF INDIVIDUAL LAYERS OF COMPRESSIBLE MATERIAL POSITIONABLE BETWEEN SAID PLATENS: AT LEAST TWO SIMULTANEOUS-CLOSURE DEVICES CONNECTED WITH SAID PLATENS FOR DISPLACING SAME SYNCHRONOUSLY WITH THE RELATIVE MOVEMENT OF SAID PLATES, SAID DEVICES EACH COMPRISING 